A friend of mine joined my server as a fresh new player, first there was no problem until he found out that trees don't grow, wheat doesn't grow either, leaves don't decay after removing the logs, he does get all the blocks and items and can use it, but some stuff just doesn't work for him, if I go to his base stuff starts to grow and leaves start to decay, it seems like he is not being recognised by the server.

Made a backup of his profile in the world folder, started fresh but same problems appears.

Ghrane